roddyama said:You had better get that router back out. With all those amps, you’re going to need more speakers.
I know how you guy feel though. I have an old Pass A40 500VA toroid with 4 X 24VAC outputs. I also have some LM3875 samples coming. Yeah, I caught the Gainclone virus too (To think, I even had my flu shot this year). Now I have to learn how to set up the production line like you and Peter. I’m thinking about a bridged Gainclone stereo sub-woofer amp. I'm guessing that I can run 2 transformer outputs and 2 bridges per channel @ about 30VDC rails and ~200wpc, give or take.
Interesting you mentioned router, as I just picked up a 1 1/2" roundover for making some speakers, and sitting on my table now, I have peerless woofers and tweeters to make a version of Bob Brines Peerless TL ( http://www.geocities.com/rbrines1 ) and also a pair of Jordan JX92S for building the Jordan TL enclosure on their website: ( http://www.ejjordan.co.uk/enclosures.html ).
My table saw comes in the mail tommorrow from amazon, and Jordan and I ordered 24 Tangband w3-871s 3" full range drivers ($10 each), and are making 3 pairs each. (girlfriend wants some computer speakers, a pair for me, and a pair for my mom's birthday).
I think that I have projects lined up for the next couple of months. It should be an interesting semester. I borrowed some of my parents tools as well, so we will have a woodshop setup.
I am addicted to audio projects.After listening to the mono gainclone for a couple of hours while working on various things, it already sounds a bit better. I am amazed at how this amplifier can be built in a couple of hours, and could possibly sound better then my leach amp that I spent a month of free time on. It feels like cheating, making an amplifer with small heatsinks, 2 resistors, 3 caps and a pot... My aleph projects (x and 5) are still on hold. I am still waiting on a good deal for power supply caps.
How are your projects coming along? It would be interesting to see how the sub amp comes along. I need to make a sub amp for my girlfriend (making her a sealed shiva sub also). I have John Pomann's active subwoofer crossover that I will use with it.
--
Brian
grimberg said:
Do you know if the review is available on-line? What is the URL?
I think you can be more creative than that..
http://www.tnt-audio.com/ampli/amps.html
Niels.
I got a couple emails by people asking if they could buy my Aleph X boards thinking I was going to build a gainclone instead, one was kind of scathing. Well, forget it people 
I am still building my Aleph Xs and a couple Gainclones as well. I was speaking metaphorically in relation to Peter's post right before mine. Sheesh...
I am still building my Aleph Xs and a couple Gainclones as well. I was speaking metaphorically in relation to Peter's post right before mine. Sheesh...
Here is something that popped up...
on the AmpChip Forum. I'd like to see what others think.
__________________________________________________
Another mod... Anthony Dockrill
Hi,
The Class A mod as mentioned previously (1.5k resistor from amp out to v-) to my ears makes the amp much better but I've just tried something that's even better.
A Constant Current Source I think takes this amp to an all time high in my books. It makes sense that a CCS would be better then a resistor as the resistor would be interacting with the output as it varied with the input signal.
The CCS I used is a simple mosfet stage. I used some 100W mosfets I had handy but the best bet is to use something like a IRF510 or IRF520.
The output of the amp is connected to a 100ohm resistor, which is connected to the drain of the mosfet. The gate of the mosfet is connected to a 200ohm resistor which is then connected to the + of 4 AA batteries. The battery pack forms a 6V reference for the mosfet. The source of the mosfet is connected to a 100 ohm resistor which then connected to the -V supply. The - of the battery reference is also connected to the - supply.
If you want to change the current draw just fiddle with the resistor on the source. The above values give 18.5ma on the mosfets I'm using at the moment.
A cascade mosfet arrangement should be better in theory but I am worried that there will not be enough voltage headroom for the CCS to work at maximum output. I will try a cascade and report back.
Cheers,
Anthony
Unregistered User
1/5/03 3:58:24 pm
Reply
on the AmpChip Forum. I'd like to see what others think.
__________________________________________________
Another mod... Anthony Dockrill
Hi,
The Class A mod as mentioned previously (1.5k resistor from amp out to v-) to my ears makes the amp much better but I've just tried something that's even better.
A Constant Current Source I think takes this amp to an all time high in my books. It makes sense that a CCS would be better then a resistor as the resistor would be interacting with the output as it varied with the input signal.
The CCS I used is a simple mosfet stage. I used some 100W mosfets I had handy but the best bet is to use something like a IRF510 or IRF520.
The output of the amp is connected to a 100ohm resistor, which is connected to the drain of the mosfet. The gate of the mosfet is connected to a 200ohm resistor which is then connected to the + of 4 AA batteries. The battery pack forms a 6V reference for the mosfet. The source of the mosfet is connected to a 100 ohm resistor which then connected to the -V supply. The - of the battery reference is also connected to the - supply.
If you want to change the current draw just fiddle with the resistor on the source. The above values give 18.5ma on the mosfets I'm using at the moment.
A cascade mosfet arrangement should be better in theory but I am worried that there will not be enough voltage headroom for the CCS to work at maximum output. I will try a cascade and report back.
Cheers,
Anthony
Unregistered User
1/5/03 3:58:24 pm
Reply
CCS
Hi,
A couple of small things I'd like to point out. The CCS I described on Amp Chip DIY is just something I put together with parts on hand is not a CCS load one should get too excited about. It does sound better then the resistor mod.
I am in the process of building a proper cascode constant current source (or current sink as it is used in this application). I will let you know how it goes.
As a couple people have pointed out this not a class A amp and this mod does not make it one. What I think is going on is the bias current at zero signal is being changed and the amp simply sounds better for the change.
My clone now sounds so good as a once dedicated valve DIY guy I have next to no interest in making another valve amp again.....
Cheers,
Anthony
Hi,
A couple of small things I'd like to point out. The CCS I described on Amp Chip DIY is just something I put together with parts on hand is not a CCS load one should get too excited about. It does sound better then the resistor mod.
I am in the process of building a proper cascode constant current source (or current sink as it is used in this application). I will let you know how it goes.
As a couple people have pointed out this not a class A amp and this mod does not make it one. What I think is going on is the bias current at zero signal is being changed and the amp simply sounds better for the change.
My clone now sounds so good as a once dedicated valve DIY guy I have next to no interest in making another valve amp again.....
Cheers,
Anthony
Peter Daniel said:To make an even better comparison: Aleph-X is like your beloved wife and Gaincard is like your mistress. If you truly in love with the first one, you will stay with her forever.
I want to build the gainclones as many as my ...?!?!
O my Dog! Mr Nelson Pass counting towards public number of his ...!!! http://www.diyaudio.com/forums/showthread.php?s=&threadid=9545&perpage=15&pagenumber=1
JH
Banned
Joined 2002
For a CCS, would a bank of batteries put in (a couple in series and a couple in parallel) create a sort of buffer for a trickle charger (wall wart type)? I know these things can be noisy but they are cheap and would supply the current you need. I think I remember reading that the draw the batteries put on the circuit helps filter noise from a noisy DC source. You could add a RC circuit or similar to help filter the noise.
I got the cable and ends from parts-express. I don't really know if the cable is any more quality than anything else, but I'm satisfied with it.JasonL said:
But speaking of cables, I had a question.. These gainclones seem to be somewhat sensitive to noise and interference. That being said, what kind of cables should I use to connect the amp to the speakers? I'm making some speakers/gainclones for my father, and he is going to be placing the amplifier as far as 60 feet away from the speakers. Can I get away with using this 16 gauge stuff without significantly damaging the audio?
--Jordan
regarding the feedback resistors. Has anyone tried using different values for this resistor and see how it effects the sound of the amplifier?
The datasheet has it as 20k in a non-inverted setup.
How would different values for this resistor effect the operation of the amplifier?
It effects the gain, right? Would having less gain sound better? Right now, I can turn my gainclone up and it goes plenty loud for my speakers. 4 ohm speakers with +/- 25vdc supply voltages.
Increasing the resistor value would decrease the gain in the inverted configuration?
--
Brian
The datasheet has it as 20k in a non-inverted setup.
How would different values for this resistor effect the operation of the amplifier?
It effects the gain, right? Would having less gain sound better? Right now, I can turn my gainclone up and it goes plenty loud for my speakers. 4 ohm speakers with +/- 25vdc supply voltages.
Increasing the resistor value would decrease the gain in the inverted configuration?
--
Brian
Alright,
I went surplus shopping and picked up some 160k, 180k and 270k resistors and will try them for the nfb resistor in future versions.
Anyone use Allen Bradley carbon comp. resistors? Thorsten recommended them as sounding better for the gainclone. I am wondering if the best way to match them would be bake them in a convection oven at 80C for a day, then match them. Anyone have any suggestions on a better way? I have a couple hundred of each value, so they should match up alright. (picked up a bunch of the NOS 50 packs of the 5% 1/4 watt packages)
--
Brian
I went surplus shopping and picked up some 160k, 180k and 270k resistors and will try them for the nfb resistor in future versions.
Anyone use Allen Bradley carbon comp. resistors? Thorsten recommended them as sounding better for the gainclone. I am wondering if the best way to match them would be bake them in a convection oven at 80C for a day, then match them. Anyone have any suggestions on a better way? I have a couple hundred of each value, so they should match up alright. (picked up a bunch of the NOS 50 packs of the 5% 1/4 watt packages)
--
Brian
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